Reliability Assessment Guidebook

81 Pages·1.156 MB·English

by  Village B.

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Version 2.1

May 2010
Reliability Assessment Guidebook Table of Contents

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Planning Committee Reliability Guidelines .................................................................................... iiv

Guidebook Overview ..........................................................................................................................1

Chapter 1—NERC Reliability Assessment ........................................................................................3

Chapter 2—Bulk Power System Planning for Reliability ..................................................................9 
Guidelines for Long-Term Planning ...........................................................................................9 
System Reliability Characteristics & Guidelines for Bulk Power System Planning ................11 
Guidelines for Reliability Assessment ......................................................................................13 
Guidelines for Sufficient Planning Margins Supporting Operating Reliability & Adequacy ..14 
Definition of “Adequate Level of Reliability” .........................................................................15 
Summary ...................................................................................................................................16

Chapter 3—Demand and Load Forecasting ......................................................................................17 
How Regional Entities Develop their Load Forecasts ..............................................................17 
Guidelines for Modeling of Demand ........................................................................................19 
How NERC Develops its Load Forecast Bandwidths ..............................................................22 
Guidelines for Demand-Side Management (DSM) Resources .................................................23 
How Demand Side Management Data is Developed ................................................................27 
Incorporating Demand Response in a Reliability Assessment .................................................28 
Incorporating Energy Efficiency in a Reliability Assessment ..................................................29 
Guidelines for Demand Modeling in a Reliability Assessment ................................................30

Chapter 4—Supply & Transactions ..................................................................................................31 
How Regional Entities Identify Resources ...............................................................................31 
How NERC Categorizes Capacity ............................................................................................31 
How NERC Categorizes Transactions ......................................................................................35 
Guidelines for Supply & Transactions ......................................................................................36

Chapter 5—Resource Adequacy Assessment ...................................................................................39 
Regional Resource Assessment Procedures ..............................................................................40 
Issues & Considerations in Resource Assessment ....................................................................42 
How NERC Computes Reserve Margins ..................................................................................46 
          Guidelines for Resource Deliverability ....................................................................................47

Chapter 6—Transmission Reliability Assessment ............................................................................49 
Guidelines for Transmission Reliability Assessment ...............................................................50

Chapter 7—Operational Issues .........................................................................................................52 
Guidelines for Operational Issues .............................................................................................52

Chapter 8—Other Issues ...................................................................................................................53 

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Reliability Assessment Guidebook Table of Contents
Chapter 9—Scenario Assessment .....................................................................................................54 
Background ...............................................................................................................................54 
Guidelines for Submittal ...........................................................................................................55

Chapter 10—NERC Reliability Assessment Procedures ..................................................................60 
Data Requests to the Regions ...................................................................................................65 
RAS Review of Regional Data and Reliability Assessments ...................................................66 
Resource Adequacy Assessment ...............................................................................................66 
Transmission Adequacy and Security Assessment ...................................................................66 
Regional Process Review ..........................................................................................................67 
Reporting of Assessment Result ...............................................................................................67 
Data Request to the Regions .....................................................................................................67 
Operational Assessment ............................................................................................................68 
Reporting of Assessment Results..............................................................................................69

Appendix I: Resource Adequacy Methods .......................................................................................71 
Probabilistic Methods ...............................................................................................................71 
Deterministic Approaches and Methods: ..................................................................................75

Appendix II: Committee & Staff Organization Charts .....................................................................76

Appendix III: References ..................................................................................................................77 

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Reliability Assessment Guidebook Planning Committee Reliability Guidelines
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Reliability Guidelines

Reliability Guidelines1 are documents that suggest approaches or behavior in a given technical
area for the purpose of improving reliability. Reliability guidelines are not binding norms or
mandatory requirements. Reliability guidelines may be adopted by a responsible entity in
accordance with its own facts and circumstances2.

Approval of Reliability Guidelines

Because reliability guidelines contain suggestions that may result in actions by responsible
entities, those suggestions must be thoroughly vetted before a new or updated guideline receives
approval by a technical committee. The process described below will be followed by the
Planning Committee:

a) New/updated draft guideline approved. The Planning Committee approves release of a
new or updated draft guideline developed by one of its subgroups or the committee as a
whole.
b) Post draft guideline for industry comment. The draft guideline is posted for industry
wide comment for forty-five (45) days. If the draft guideline is an update, a redline
version against the previous version must also be posted.
c) Post industry comments and responses. After the public comment period, the Planning
Committee posts the comments received as well as its responses to the comments. The
committee may delegate the preparation of responses to a committee subgroup.
d) New/updated guideline approval and posting. A new or updated guideline which
considers the comments received, is approved by the sponsoring technical committee and
posted on the NERC Web site. Updates must include a revision history and a redline
version against the previous version.
e) Guideline updates. After posting a new or updated guideline, the Planning Committee
will continue to accept comments from the industry via a Web-based forum where
commenters may post their comments.
i. Each quarter, the Planning Committee will review the comments received. At any
time, the Planning Committee may decide to update the guideline based on the
comments received or on changes in the industry that necessitate an update.
ii. Updating an existing guideline will require that a draft updated guideline be
approved by the Planning Committee in step “a” and proceed to steps “b” and “c”
until it is approved by the Planning Committee in step “d.”

1 Planning Committee Charter, see Appendix 4 at: http://www.nerc.com/docs/pc/Charter_PC_Approved_29Oct2008.pdf
2 Standards Committee authorization is required for a reliability guideline to become a supporting document that is
posted with or referenced from a NERC Reliability Standard. See Appendix 3A in the NERC’s Rules of Procedure
under “Supporting Documents.”
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Reliability Assessment Guidebook Guidebook Overview

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Background
The NERC Planning Committee agreed at their February 2008 meeting that a Reliability
Assessment Guidebook should be developed to support the enhancement of seasonal and Long-
Term Reliability Assessments. The goals of this Guidebook are to:
 Improve consistency and transparency of assessments
 Provide for more granular assessments
 Outline the process to assess emerging industry issues
 Establish a core framework for NERC when conducting comprehensive and independent
assessments

This Guidebook provides a reference for Regional Entities and Registered Entities, and is
organized to clarify current reliability assessment practices and objectives. The intent is to
document practices and provide a comprehensive review for reliability assessments. The
Guidebook reviews the elements and issues that go into making the NERC reliability
assessments and the final NERC reports as consistent, uniform and credible as possible by
explaining the need for:
1. Input from the Regional Entities, so that external audiences (e.g., FERC, media,
Congress, CEOs, etc.) can obtain a clear understanding about the anticipated
performance, strength and concerns of the bulk-power system over seasonal and long-
term periods.
2. NERC’s and the Regional Entities’ assessments are presented in a consistent and
conforming manner, so the overall reports are effectively comprehensive and complete.
The Regional Entities will develop the foundation and support for assessment practices, and as
such, the Guidebook articulates the corresponding foundation, support and recommendations for
NERC’s independent review, providing a uniform delivery of the reliability assessment. The
Reliability Assessment Guidebook is not a standard or requirement. The recommendations and
guidance discussed are not enforceable as requirements under any NERC Standard.

Members of the Reliability Assessment Guidebook Task Force (RAGTF)
 Jeff Mitchell (Chair)
 Randy Hubbert (SERC)
 Vince Ordax (FRCC)
 Mark Lauby (NERC)
 John Moura (NERC)

Reliability Assessment Reference Documents
The most current reference documents are available on the RAS website at:

http://www.nerc.com/filez/ras.html

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Reliability Assessment Guidebook Guidebook Overview
Reliability Assessment Guidebook Lifecycle

The Reliability Assessment Guidebook is a “living” document and as Planning Committee
Reliability Guideline it will be updated, as applicable per the Planning Committee Charter. The
Reliability Assessment Guidebook Task Force will continue to collect comments. The task force
will respond to the comments and post them on the NERC website at:
http://www.nerc.com/filez/ragtf.html. Each quarter, the Planning Committee will review the
comments received and revise the document, as needed.

Figure 1: Reliability Assessment Guidebook Lifecycle

Reliability
Assessment
Guidebook
V1.0
RAGTF will
incorporate
comments into a
revised
RAGTF to Guidebook
Post for a 45
continue to
day industry-
accept
wide comment
comments
period
Comments
Reliability
and responses
posted to
Assessment NERC Website
Guidebook 
Guidebook
Ver. X.X +.1
Lifecycle
posted to
NERC Website
RAGTF will
PC Approval incorporate
comments
into a revised
Present Guidebook
revised
Guidebook to
PC for
approval

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Reliability Assessment Guidebook NERC Reliability Assessment

CChhaapptteerr 11——NNEERRCC RReelliiaabbiilliittyy AAsssseessssmmeenntt

The North American Electric Reliability Corporation’s (NERC) mission is to ensure the bulk
power system3 in North America is reliable. To achieve this objective, NERC develops and
enforces reliability standards; monitors the bulk power system; assesses and reports on future
adequacy; and offers education and certification programs to industry personnel. NERC is a
non-profit, self-regulatory organization that relies on the diverse and collective expertise of
industry participants that form its various committees and sub-committees. It is subject to
oversight by governmental authorities in Canada and the United States (U.S.)4

ERCOT RFC
Electric Reliability ReliabilityFirst
Council of Texas Corporation

FRCC SERC

Florida Reliability SERC Reliability

Coordinating Council Corporation

MRO SPP
Midwest Reliability Southwest Power Pool,
Organization Incorporated

NPCC
WECC
Northeast Power
Western Electricity
Coordinating Council,
Coordinating Council
Inc.

NERC assesses and reports on the reliability and adequacy of the North American bulk power
system divided into the eight Regional areas. The users, owners, and operators of the bulk power
system within these areas account for virtually all the electricity supplied in the U.S., Canada and
a portion of Baja California, Mexico5.

NERC’s primary role in providing reliability assessment is to identify areas of concern to the
reliability of the North American bulk power system and to make recommendations for their
remedy. NERC cannot order construction of additional generation or transmission or adopt
enforceable standards having that effect, as that authority is explicitly withheld by Section 215 of

3 The part of the overall electricity system that includes the generation of electricity and the transmission of electricity over high-
voltage transmission lines to distribution companies. This includes power generation facilities, transmission lines,
interconnections between neighboring transmission systems, and associated equipment. It does not include the local
distribution of the electricity to homes and businesses.
4 On June 18, 2007, the U.S. Federal Energy Regulatory Commission (FERC) granted NERC the legal authority to enforce
reliability standards with all U.S. owners, operators, and users of the bulk power system, and made compliance with those
standards mandatory, as opposed to voluntary. NERC has similar authority in Ontario and New Brunswick, and is seeking to
extend that authority to the other Canadian provinces. NERC will seek recognition in Mexico once the necessary legislation is
adopted.
5 Section 39.11(b) of the U.S. FERC’s regulations provide that: “The Electric Reliability Organization shall conduct assessments
of the adequacy of the Bulk-Power System in North America and report its findings to the Commission, the Secretary of
Energy, each Regional Entity, and each Regional Advisory Body annually or more frequently if so ordered by the
Commission.”

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Reliability Assessment Guidebook NERC Reliability Assessment
the U.S. Energy Policy Act of 20056. In addition, NERC does not make any projections or draw
any conclusions regarding expected electricity prices or the efficiency of electricity markets.

The Seasonal Reliability Assessments and Long-Term Reliability Assessment (LTRA) provide key
findings, a high-level assessment of future resource adequacy, an overview of projected
electricity demands and demand response resources, planned and proposed generation and
transmission additions, emerging issues and their potential reliability impacts, operational
reliability trends, Regional assessment highlights, scenario analysis update and Regional self-
assessments. The LTRA represents NERC’s independent judgment of the reliability and
adequacy of the bulk power system in North America for the coming ten years.

A distinction must be made to the recommendations outlined in this Guidebook for Reliability
Assessments. This Guidebook serves as guidelines for assessing resource adequacy, as done by
the Regional Entities and NERC. These guidelines do not attempt to support assumptions,
models, methodologies used by entities responsible for determining (i.e. setting) resource
adequacy requirements for their respective jurisdictions. The two activities are distinctly
different in nature, although they may share some commonality (for instance, regarding the
analytic tools used).

Assessment Preparation
NERC prepares the Seasonal and Long-Term Reliability Assessments7 with support from the
Reliability Assessment Subcommittee (RAS) under the direction of NERC’s PlanningCommittee
(PC), shown in Figure 2.

Figure 2: NERC Planning Committee Organization Chart

6 http://frwebgate.access.gpo.gov/cgi-bin/getdoc.cgi?dbname=109_cong_bills&docid=f:h6enr.txt.pdf
7 Unlike the Energy Information Administration’s (EIA) Annual Energy Outlook (for example the 2008 report can be found at
http://www.eia.doe.gov/oiaf/aeo/pdf/0383(2008).pdf), NERC’s report focuses exclusively on bulk power system reliability
with data and information provided by industry experts, representing a variety NERC stakeholders.

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Reliability Assessment Guidebook NERC Reliability Assessment
NERC prepares the Seasonal and Long-Term Reliability Assessments8 with support from the
Reliability Assessment Subcommittee (RAS) under the direction of NERC’s Planning
Committee (PC), shown in Figure 2. The reports are based on data and information submitted by
each of the eight Regional Entities submitted in March, May and September each year and
periodically updated throughout the process.9 Instructions on data submittal and timely subjects
for group development within the self-assessments are provided to each Regional Entity
approximately three-to-five months prior to submittal of the data and narratives. Any other data
sources consulted by NERC staff are identified in the report.

NERC uses an active peer review process in developing reliability assessments. The peer review
process takes full advantage of industry subject matter expertise from many sectors of the
industry. This process also provides an essential check and balance for ensuring the validity of
the information provided by the Regional Entities.

Each Region prepares its data and a self assessment. Each of the Regional self-assessments is
assigned to two-to-four RAS members from other Regions for an in-depth and comprehensive
review of the data and information. Reviewer comments are discussed with the Regional
Entity’s representative and refinements and adjustments are made as necessary. The Regional
self-assessments and data are then subjected to scrutiny and review by the entire subcommittee.
This review ensures members of the subcommittee are fully convinced that each Regional self-
assessment and data is accurate, thorough, and complete. The report is also reviewed by the
Operating Committee (OC), while the entire document, including the Regional self-assessments,
is then reviewed in detail by the Member Representatives Committee (MRC) and NERC
management. The report is endorsed by the PC before being submitted to NERC’s independent
Board of Trustees for final approval (See Appendix II for organization charts). This
comprehensive vetting process ensures complete stakeholder agreement on NERC’s independent
assessment and the self-assessment from the Regional Entities, as well as supports the mission of
NERC as a self-regulatory organization.

For NERC’s Seasonal and Long-Term Reliability Assessments, the baseline information on
future electricity supply and demand is based on several assumptions:10

 Supply and demand projections are based on industry forecasts submitted by a certain
date. Any subsequent demand forecast or resource plan changes may not be fully
represented.

8 Unlike the Energy Information Administration’s (EIA) Annual Energy Outlook (for example the 2008 report can be found at
http://www.eia.doe.gov/oiaf/aeo/pdf/0383(2008).pdf), NERC’s report focuses exclusively on bulk power system reliability
with data and information provided by industry experts, representing a variety NERC stakeholders.
9 See http://www.nerc.com/files/concepts_v1.0.2.pdf for more background on reliability concepts used in this report.
10 Forecasts cannot precisely predict the future. Instead, many forecasts report probabilities with a range of possible outcomes.
For example, each Regional demand projection is assumed to represent the expected midpoint of possible future outcomes.
This means that a future year’s actual demand may deviate from the projection due to the inherent variability of the key factors
that drive electrical use, such as weather. In the case of the NERC Regional projections, there is a 50 percent probability that
actual demand will be higher than the forecast midpoint and a 50 percent probability that it will be lower.

For planning and analytical purposes, it is useful to have an estimate not only of the expected of possible future outcomes, but
also of the distribution of probabilities around the projection. Accordingly, the Load Forecasting Working Group (LFWG)
develops for each an upper and lower ten percent confidence band around the NERC Regional demand and energy projections.
This means there is an 80 percent probability that future demand and energy will occur within these bands. Concurrently, there
is a ten percent chance future outcomes could be less than the lower band and a ten percent chance future outcomes could be
higher than the upper band. The high and low bands around the demand forecasts are depicted in the charts with each Region's
self assessment

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Reliability Assessment Guidebook NERC Reliability Assessment
 Peak demand and reserve margins are based on average weather conditions and assumed
forecast economic activity at the time of submittal. Weather variability is discussed in
each Regional self-assessment.
 Generating and transmission equipment will perform at historical availability levels.
 Planned outages and future generation and transmission facilities are commissioned and
in-service as scheduled and planned.
 Demand reductions expected from demand response programs will yield the forecast
results, if and when they are called on.
 Other peak demand-side management programs are reflected in the forecasts of net
internal demand.
 Firm electricity transfers between Regions are contractually arranged and occur as
projected.
NERC’s basis for an independent assessment is the data submitted to NERC from the Regional
Entities. The high level demand and supply data collection process, for reliability assessments,
is shown in Figure 3. All NERC Regions, including Canada and Mexico, provide their demand
and capacity resources information to NERC through the LTRA data collection process. U.S.
data is then submitted to EIA on behalf of the industry through the EIA Form-411.11
The Form EIA-411, “Coordinated Bulk Power Supply Program Report,” collects information
from the North American power system planners about the electricity supply, both capacity and
energy, that is needed to serve current demand and for future growth. In 2008, the Form EIA-
411 became a mandatory collection (U.S. entities only). This data can be used to examine such
issues as: the reliability of the U.S. electricity system; projections which assess future demand
growth and plans for constructing new generating and transmission facilities; and consequences
of unavailable or constrained capacity on usage of the existing generation base.
Generator Owners and Operators provide specific generator data to EIA through the EIA-860
Form12, which is then provided to NERC. The Form EIA-860 is a generator level data file that
includes specific information about generators at electric power plants owned and operated by
electric utilities and nonutilities (including independent power producers, combined heat and
power producers, and other industrials). The database contains generator-specific information
such as initial date of commercial operation, prime movers, generating capacity, energy sources,
status of existing and proposed generators, proposed changes to existing generators, county and
State location, ownership, and FERC qualifying facility status.
For Canadian and Mexican organizations, NERC has a process to collect specific generator data.
This is incorporated into the LTRA data collection forms on an annual basis. These forms mimic
those found on the Form EIA-860. This data is submitted only to NERC.

11 More information on the Form EIA-411 can be found at: http://www.eia.doe.gov/cneaf/electricity/page/eia411/eia411.html
12More information on the Form EIA-411 can be found at: http://www.eia.doe.gov/cneaf/electricity/page/eia860.html

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